Bulletproof Protective Structure

Abstract

A bulletproof protective structure (40) is described, composed of a flexible base constituted of a ballistic fabric (42) and of rigid elements (41) of ballistic material adhering to the fabric, wherein the adhesion surface of the rigid elements to the fabric is curved, so as to allow greater flexibility of the structure compared to similar known structures.

Claims

1. A bulletproof structure comprising: a flexible base including intertwined or unidirectional ballistic fibers on which rigid metallic or ceramic elements are adhered adjacent to each other, wherein a face of said elements adhering to the fibers is convex, the rigid elements adhere to the flexible base for a fraction of said convex surface, and in a plan view the rigid elements have a polygonal or pseudo-polygonal shape, such that there are no voids between sides of two abutting rigid elements.

2. The bulletproof structure according to claim 1, wherein the face of said rigid elements opposite to said convex face is flat.

3. The bulletproof structure according to claim 1, wherein a face of said rigid elements opposite to said convex face is concave, and the radius of curvature of the concave surface is lower than the radius of curvature of the convex surface, so that the thickness at the edge of the element is between 0.5 and 2 mm greater than the thickness at the center of the same element.

4. The bulletproof structure according to claim 3, wherein the radius of curvature of the concave surface is between 30 and 300 mm.

5. The bulletproof structure according to claim 1, wherein the radius of curvature of the convex surface is between 40 and 350 mm.

6. The bulletproof structure according to claim 5, wherein the radius of curvature of the convex surface is between 80 and 250 mm.

7. The bulletproof structure according to claim 6, wherein the radius of curvature of the convex surface is between 100 and 180 mm.

8. The bulletproof protective structure according to claim 1 in which, in a top view, said rigid elements have a triangular, rectangular, square or hexagonal shape.

9. The bulletproof protective structure according to claim 1, in which said rigid elements have lateral dimensions between 10 and 50 mm and thickness between 2 and 10 mm.

10. The bulletproof protective structure according to claim 1, in which the flexible base is made of aramid or ultra-high molecular weight polyethylene (UHMWPE) fibers and has a thickness between 1 and 5 mm.

11. The bulletproof protective structure according to claim 1, in which the rigid elements are made of aluminum oxide, silicon carbide or boron carbide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The invention will be described in the following with reference to the figures, wherein:

[0017] FIG. 1 shows a schematic sectional view of a generic rigid element, in a first embodiment, for the production of a bulletproof structure of the invention;

[0018] FIG. 2 shows a schematic sectional view of a rigid element, in a preferred embodiment, for the production of a bulletproof structure of the invention;

[0019] FIG. 3 shows, in plan, sectional and perspective views, a first possible rigid element for the realization of a bulletproof structure of the invention;

[0020] FIG. 4 shows, in a plan and sectional view, a possible bulletproof structure of the invention;

[0021] FIGS. 5 and 6 show, in plan and sectional views, rigid elements of bulletproof structures of the prior art.

DETAILED DESCRIPTION OF THE INVENTION

[0022] FIGS. 5 and 6 relate to ceramic elements of the prior art, and have already been described above. In the Figures relating to the invention, the dimensions are not necessarily to scale, and some dimensions can be increased to highlight constructional details of the elements and of the structures of the invention; in these Figures, moreover, an equal number corresponds to an equal element.

[0023] The bulletproof structure of the invention comprises a flexible base, made of ballistic fibers on which rigid elements are adhered which, unlike those of the known structures, have the surface adhering to the flexible base which has a convex shape and therefore is neither flat nor comprises flat portions.

[0024] These rigid elements have two main surfaces, with greater extension, destined the former to stop the bullets and the latter to adhere to the flexible base of polymer fibers, and lateral surfaces with smaller extension that in the overall structure are adjacent to each other.

[0025] In the following, the surface destined to stop the bullets will also be defined as the front surface, while the convex one, destined to adhere to the flexible base of polymer fibers, in the following will also be defined as the rear surface.

[0026] FIG. 1 shows a schematic sectional view of a generic rigid element for the realization of a bulletproof structure of the invention: the element, 10, comprises a front surface, 11, which has any geometry and is typically flat, and a convex rear surface, 12; the lateral surfaces are indicated in the figure as surfaces 13; the radius of curvature of the convex surface, 12, is between 40 and 350 mm, preferably between 80 and 250 mm and even more preferably between 100 and 180 mm.

[0027] FIG. 2 shows a schematic sectional view of a preferred embodiment of rigid element, 20, for the realization of a bulletproof structure of the invention. In this embodiment, both main faces of said rigid elements are curved surfaces, the front face 21 is concave and the rear face 12 convex, said rigid elements adhere to the flexible base for a fraction of their convex surface, and the thickness at the edge of the element is between 0.5 and 2 mm greater than the thickness at the center of the element itself. This geometry allows to lighten the rigid elements given their smaller thickness at the center with respect to the rigid element 10, and consequently to decrease the weight of the bulletproof structure as a whole; at the same time, the greater thickness at the edges with respect to the center of the elements of type 20 guarantees the necessary mechanical resistance to the impact of the bullets in this zone, which is a critical characteristic of the known bulletproof structures.

[0028] In an even more preferred embodiment, the two main faces, 12 and 21, of a rigid element of type 20 are two portions of spherical caps; in this case, the condition that the thickness at the edge of the element is between 0.5 and 2 mm greater than the thickness at the center of the element itself entails that the radius of curvature of the concave surface 21 is less than that of the convex surface 12. Depending on the lateral dimensions of a rigid element of type 20, the radius of curvature of the concave surface can vary between 30 and 300 mm; the radius of curvature of the convex surface will vary accordingly, to ensure the condition of greater thickness at the edge with respect to the center of the element.

[0029] The rigid elements, both of type 10 and of type 20, are produced with the materials that are typically used for this application, i.e. metals or, preferably, ballistic ceramics such as aluminium oxide (alumina), silicon carbide or boron carbide. The production methods for these rigid elements are well known to those skilled in the art, and generally consist in sintering powders of the aforementioned materials, typically at temperatures between 1500 and 2200° C. The advantage of the rigid elements of the invention with respect to those known (for example, those of EP 3805691 A1) is that since the two main surfaces are spherical, during their production the pressure is exerted uniformly in all their points, which ensures the maximum homogeneity of structural and mechanical characteristics of the rigid elements obtained.

[0030] In a plan view, the rigid elements of the structures of the invention may have any shape suitable for tessellating a flat surface, i.e. typically triangular, rectangular, preferably square or even more preferably hexagonal shape.

[0031] FIG. 3 shows, in plan, sectional and perspective views, a rigid element 30 with the preferred hexagonal geometry in plan, and with concave front face 21.

[0032] The lateral dimensions of the rigid elements useful for the invention, in any of the possible shapes illustrated above, may vary within wide margins; for the preferred hexagonal shape, the lateral dimensions may vary indicatively between 10 and 50 mm, while the thicknesses typically vary between 2 and 10 mm.

[0033] The flexible base is the same as the one of known bulletproof structures. This base is made with the aramid (for example Kevlar®) or ultra-high molecular weight polyethylene (UHMWPE, for example Dyneema) fibers mentioned above; the fibers can be arranged unidirectionally, variously intertwined or woven, according to methods known to those skilled in the art. The number of layers of fibers can be varied, depending on the degree of protection to be obtained; typically the flexible base has a thickness between about 1 to 5 mm.

[0034] The rigid elements are adhered to the base in polymer fibers by gluing, typically with thermoplastic elastomeric resins, for example polyurethane elastomers.

[0035] Since the gluing surface is convex, while normally the flexible base is kept in planar arrangement during the production of the structures, virtually the adhesion area would be a single point; however, to favour gluing, during the same and until the glue has solidified, a pressure is exerted on the rigid elements, so that these are partially “pushed” inside the base of polymer fibers, so that the gluing zone extends to a spherical cap. This condition is schematically represented in FIG. 4: in the upper part of the figure there is shown a sectional view of a structure 40 made of a series of rigid elements of the invention, 41, 41′, 41″, . . . , adhering to the flexible base 42 in the zones 43, 43′, 43″, . . . ; in the lower part of the figure there is instead shown a plan view of the structure 40, in which the rigid elements 41, 41′, 41″, . . . have the preferred hexagonal shape, and the dashed circular central zones represent the areas for gluing 43, 43′, 43″, . . . to the base 42. As can be seen in this last figure, the gluing zones are relatively far apart, and the base 42 is free to bend and curve between two contiguous gluing zones, while in the gluing-free zones the rigid elements 41, 41′, 41″, . . . , which are not constrained to each other, will be able to rise with respect to the base 42 while the latter is being bent. The width of the central zones 43, 43′, 43″, . . . depends on the radius of curvature of the convex surface, and therefore on the degree of flexibility desired in the final structure: a smaller radius of curvature will correspond to a smaller width of the zones 43, 43′, 43″, . . . , and therefore a greater flexibility of the final bulletproof structure; it is therefore possible with the present invention to obtain bulletproof structures with sufficient flexibility to adapt to the shapes of the body.

[0036] The bulletproof structure is then completed with an additional layer of textile material, not necessarily of ballistic type, arranged on the front part of the rigid elements, for aesthetic reasons and to favour the maintenance of the correct positioning of said elements.